"Leukemia? How did I get leukemia?" Waller kept wondering, after he was diagnosed more than a decade ago.

Then an old friend of his who's fast on the internet and scours it for news suggested an answer.

"Weren't you at Camp Lejeune?" he asked Waller.

Indeed he was. Six weeks, back in 1968, when he was a Marine during the Vietnam War.

"That water there was poisonous!" the friend told him.

For six weeks in 1968, Waller showered, drank and ate food cooked in a poisonous stew of benzene, perchloroethylene, trichloroethylene, vinyl chloride and a few other chemicals few of us can pronounce.

That was long enough, the government now acknowledges, to cause adult leukemia and seven other illnesses that afflict millions of veterans and their families.

On Tuesday, Waller and other veterans and family members who were based at Camp Lejeune and also got sick may finally get some compensation for that. The U.S. government is freeing up about $2 billion for veterans who served at least 30 consecutive days at Camp Lejeune and are struggling with at least one of the eight diseases linked to the toxic water they used while serving their country.

For years, folks didn't believe Waller and thousands of others that their illnesses - "adult" leukemia, bladder cancer, kidney cancer, liver cancer, multiple myeloma, non-Hodgkin lymphoma, Parkinson's disease and aplastic anemia - were linked to their time at the country's largest Marine base in Jacksonville, North Carolina.

"Denied, denied, denied," was all they heard in response to their medical claims.

"'We're not going to take your case' is what I kept getting," Waller said.

But then Waller met Rebekah Mason, an attorney at the Legal Counsel for the Elderly who specializes in helping veterans get the benefits they are entitled to - especially in this case.

"It's so complicated, all of it," she said.

She has patiently explained the paperwork, the benefits, the numbers to Waller.

"It would be nice to get a little bit of help," said Waller, after easing himself down on the edge of his bed with the help of his fire-engine red walking cane.

Right now, this 68-year-old veteran lives in a subsidized apartment in downtown Washington, D.C., on $731 a month. That's all he gets to pay for housing, food and the medicines that his benefits don't cover. He could be entitled to another $1,000-a-month because of his exposure to the toxic water.

The Marines first found evidence that the water at the camp was contaminated in the 1980s. But it took far longer for anyone to investigate the health risks. Meanwhile, Marines and their families got sick, and babies died.

Even after Congress passed a bill in 2012 acknowledging the harm done by the water, it left victims struggling to get their health-care bills paid. Like Waller, their claims were repeatedly denied, and a backlog grew into the hundreds of thousands.

Just a few days before leaving office, President Barack Obama agreed to pay out a total of more than $2 billion to veterans exposed to the contaminated drinking water. To qualify, they have to show a diagnosis of one of those eight diseases and evidence they served at least 30 days between Aug. 1, 1953, and Dec. 31, 1987.

It's called "presumptive status." And it's historic because it also allows vets who never served on foreign soil during wartime, like Waller, to get compensation for harm done at home.

And Waller hopes it will make his life easier. The leukemia left him unable to do custodial work, and he has been struggling ever since.

But many other veterans aren't aware of the contaminated water or the impact it had on their health. With nearly a million people eligible for help, the government isn't reaching out to all of them. It's up to them to file their own claims.

"If they don't ask for it, the (Department of Veterans Affairs) won't give it to you," Mason said.